FE206E in FE208E Sigma Cabinet - Question about Bass - diyAudio
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Old 10th September 2007, 12:01 PM   #1
wixy is offline wixy  Australia
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Default FE206E in FE208E Sigma Cabinet - Question about Bass

I just finally, finalllly finished my FE208E Sigma cabinets for the FE206E driver, which I started back in February.

I fired them up for the first time properly tonight. First impressions were really nice mids and highs, but the bass to me sounded like it lacked impact and wasn't very well defined. Didn't seem particularly deep. I'm not sure what I am supposed to expect however.

Just wondering what I can do to improve the bass?

My source is a Consonance Droplet CDP and the amp I have switched between a Kingrex T20 t-amp and an EL34 SET amp, but without noticing much difference.

Below are a couple of photo's of the damping I have used. It is just standard polyester wadding. I have used a single layer behind the driver and 2 layers in the bottom section (the locations recommended in the Fostex plans).

I know there are quite a few other people who have built this combo, I'd be interested to hear your impressions on the bass.

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Old 10th September 2007, 03:23 PM   #2
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Pull all the damping out for a start and gradually add more to taste -that looks a bit over-damped to me. My mate Simon found exactly the same issue & ended up using very thin laminate floor-underlay to line the last parts of the cabinet -that's all they needed with his Sigma units. You might find his write-up of his build interesting, especially his comments near the bottom of the page re damping: http://www.atrj13.dsl.pipex.com/na-f..._rear_horn.htm

Give the drivers a good thrashing with bass-heavy material for a week to loosen them up as well. Remember too that horn bass isn't like what you'll be used to from reflex etc cabinets -the presentation is quite different: much larger in scale, and not (as) resonant.
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Old 10th September 2007, 07:10 PM   #3
Puffin is offline Puffin  United Kingdom
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I have built the 208 cabinet for the 206E and it takes quite a long time for everything to come right (9 months and I think that they are about there). I have great bass,not neccessarily the deepest, but great quality and tight as a drum.

It would take something very special to prize these out of the room. I use a modified Tripath amp and modified PS1. Fantastic sound.
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Old 10th September 2007, 10:26 PM   #4
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I build them in a couple of week. Very thin layer of absorbing, just like fostex raccomends. Great from the beginning with no further modding, but by speakers were not new as yours.

I have a t-amp, but it has the less amound of bass of the amplifiers I tried, and it has also too much high to use with this speakers. Now I use an hafler amplifier. Also the amc soound great.
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Old 10th September 2007, 11:12 PM   #5
ronc is offline ronc  United States
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As Scott mentioned, wayyyyyy to much stuffing.Stuffing a FC with a lite fibrous material will act as a low frequency energy absorber.
Its like a pressure spring, or better yet think the old glass packed mufflers. (Showing my age again).
The only absorber i reccommend is the likes of a closed cell styrofoam positioned at a point or area where there will be a concentration of higher unwanted frequencies. And there at a minimum.
Also try tuning the horn/driver in with some added series resistance. Start with one (1) ohm and add until you get the sound you want. Be sure to use higher quality non-inductive resistors.

ron

(working on a 206/208 Austin, along with thermal dissapation/induction/retention and its effect on grain growth and boundary effect. Believe it or not , its very interesting)
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Old 11th September 2007, 12:28 AM   #6
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I have those horns now with the FE207E. When I first built I had the 208 Sigmas and they were bass lite for at least 50 or 60 hours. Then slowly over time I started to get more bass output.

I didn't have quite as much damping material as you but eventually ended up pulling it all out and lining the bottom and sides with felt. I also have about .5lbs cu. ft. damping material from the throat to the end of the first fold. Sounded very good down to about 45Hz at that point. When I added about 3 ohms of series resistance and a T90A supertweeter with an L-pad, they sounded great and seem to reach nicely down to 40 Hz.
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Old 11th September 2007, 12:47 AM   #7
wixy is offline wixy  Australia
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Thanks guys, I'll investigate with pulling all the damping out tonight and report back. Will also see if I can get some laminate floor underlay to try.
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Old 11th September 2007, 09:42 AM   #8
wixy is offline wixy  Australia
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Well I pulled out all of the damping. The bass now goes lower, although I'm not overly satisfied (perhaps i'm expecting too much from a fullrange driver). However, the bass still doesn't sound 'right' to me. It is not particularly articulate and controlled. I'm not sure exactly what 'fast' is supposed to sound like, but I don't get that impression. Everything else about these speakers sounds wonderful.

Should I be putting them closer/further from the rear/side walls?

Would spikes help a great deal?

Would the curvy chang satisfy me more? (i'd love an excuse to build the curvy chang :P).
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Old 11th September 2007, 10:50 AM   #9
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Quote:
Originally posted by ronc
As Scott mentioned, wayyyyyy to much stuffing.Stuffing a FC with a lite fibrous material will act as a low frequency energy absorber.

...

ron


I guess the same applies for the FE108E Sigma, doesn't it? I stuffed mine with quite some sheep whool. They can be seen here.

Back Loaded Horn with FOSTEX, some questions...

Too much? (Well, I'm afraid it is...)

Well, since they are already assembled (glue all the way), what is there I could do? I like their sound, but a little more bass wouldn't hurt.
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Old 11th September 2007, 10:57 AM   #10
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The 206 in the 208 box should be usable to ~40Hz. Make sure they're well away from side-walls & give the drivers some time to loosen up if they're new.
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